EF CORE 6使用事务。entity framework

如果出现错误:The connection is already in a transaction and cannot participate in another transaction.可以进行一下判断

var transaction = Database.CurrentTransaction ?? Database.BeginTransaction()

Try to use this helper function for creating a new transaction:

public CommittableTransaction CreateTransaction() 
    => new System.Transactions.CommittableTransaction(new TransactionOptions()
    {
        IsolationLevel = System.Transactions.IsolationLevel.ReadCommitted
    });

Using the Northwind database as example database, you can use it like:

public async Task<int?> CreateCategoryAsync(Categories category)
{         
    if (category?.CategoryName == null) return null;
    using(var trans = CreateTransaction()) 
    {
        await this.Context.Categories.AddAsync(category);
        await this.Context.SaveChangesAsync();
        trans.Commit();
        return category?.CategoryID;
    }
}

And then you can call it from another function like:

/// <summary>Create or use existing category with associated products</summary>
/// <returns>Returns null if transaction was rolled back, else CategoryID</returns>
public async Task<int?> CreateProjectWithStepsAsync(Categories category)
{
    using var trans = CreateTransaction();
    int? catId = GetCategoryId(category.CategoryName) 
                ?? await CreateCategoryAsync(category);
    if (!catId.HasValue || string.IsNullOrWhiteSpace(category.CategoryName))
    {
        trans.Rollback(); return null;
    }
    var product1 = new Products()
    {
        ProductName = "Product A1", CategoryID = catId
    };
    await this.Context.Products.AddAsync(product1);
    var product2 = new Products()
    {
        ProductName = "Product A2", CategoryID = catId
    };
    await this.Context.Products.AddAsync(product2);
    await this.Context.SaveChangesAsync();
    trans.Commit();
    return catId;
}

To run this with LinqPad you need an entry point (and of course, add the NUGET package EntityFramework 6.x via F4, then create an EntityFramework Core connection):

// Main method required for LinqPad
UserQuery Context;
async Task Main()
{
    Context = this;
    var category = new Categories()
    {
        CategoryName = "Category A1"
        // CategoryName = ""
    };
    var catId = await CreateProjectWithStepsAsync(category);
    Console.WriteLine((catId == null) 
           ? "Transaction was aborted." 
           : "Transaction successful.");
}

This is just a simple example - it does not check if there are any product(s) with the same name existing, it will just create a new one. You can implement that easily, I have shown it in the function CreateProjectWithStepsAsync for the categories:

int? catId = GetCategoryId(category.CategoryName) 
            ?? await CreateCategoryAsync(category);

First it queries the categories by name (via GetCategoryId(…)), and if the result is null it will create a new category (via CreateCategoryAsync(…)).

Also, you need to consider the isolation level: Check out System.Transactions.IsolationLevel to see if the one used here (ReadCommitted) is the right one for you (it is the default setting).

What it does is creating a transaction explicitly, and notice that here we have a transaction within a transaction.

原文：https://stackoverflow.com/questions/70958670/how-to-nest-transactions-in-ef-core-6